Thermoelectric materials including Type I clathrate structures may be used at least for power generation applications. Such structures may be suitable for such applications due, at least in part, to their low lattice thermal conductivity values. However, such structures may be unsuitable for intermediate temperature applications (e.g., between about 500 K and about 1000 K), at least because the maximum thermoelectric figure of merit, ZT, is generally less than 1 at about 1000 K.